finding range of values which line meet curve

helloying · #1 $Old$ October 23rd, 2009, 12:35 AM

find the values of k for which the line y= x+2 meets the curve y² + (x+k)²=2
i sub (x+2)² into y²

the i got 2x² + 4x +2 -2k +k² = 0

then b² -4ac is more than or equal zero.

i got 4² -(4)(2)(2-2k+k²)
--> 8k² +16

but my ans was not correct. the range of k is 0 to 4.i didnt get that

earboth · #2 $Old$ October 23rd, 2009, 12:39 AM

Quote:

Originally Posted by helloying $View Post$

find the values of k for which the line y= x+2 meets the curve y² + (x+k)²=2
i sub (x+2)² into y²

the i got 2x² + 4x +2 -2k +k² = 0 <<<<<< this line should read 2x² + 4x +2 + 2kx +k² = 0

then b² -4ac is more than or equal zero.

i got 4² -(4)(2)(2-2k+k²)
--> 8k² +16

but my ans was not correct. the range of k is 0 to 4.i didnt get that

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